The present technology relates generally to the use of a laser array, including an array of vertical-cavity surface-emitting lasers (VCSEL), in powder bed fusion additive manufacturing (PBFAM) systems and processes to allow for the creation of full patterns simultaneously to facilitate higher build speeds.
Additive manufacturing is a technology that enables the “3D-printing” of components of various materials including metals, ceramics and plastics. In additive manufacturing, a part is built in a layer-by-layer manner by leveling, for example, metal powder and selectively fusing the powder within a layer using a high-power laser or electron beam. After each layer, more powder is added and the laser patterns the next layer, simultaneously fusing it to the prior layers to fabricate a complete component buried in a powder bed. Additive manufacturing systems and processes are used to fabricate precision three-dimensional components from a digital model.
Current systems and processes are limited in speed by the time needed to fully scan out each part layer in a serial manner using a single scanning mirror to direct a high power laser beam along the outline of one layer of the part to be made. Once the outline of the part is complete, the scanner directs the beam to the region between the inner and outer walls to fill in the material. In each process, the laser melts a thin layer of powdered metal to melt the metal onto the previous layer produced. Once a layer is made, a recoater bar moves across and adds another layer of powder and the process with the laser is repeated. Each layer can take several seconds to a few minute to complete with many thousands of layers needed to make a part.
An alternate way to build a full section at a time is to use a mask which only lets a small area of a wide beam to the powder at one time. A disadvantage of this approach is it is very laser power inefficient, requiring the dumping of most of the laser power.
In making a build in current powder bed systems, the laser beam or electron beam is used to scan a layer of powder to sinter and melt the desired pattern in the layers of the powder bed. The typical scanning time for such systems per layer is in the range of 70-100 seconds. For some applications, the build can require days of processing time. One application of DMLM is in the fabrication and repair of airfoils for gas turbine engines for aircraft. The geometries of the airfoils are difficult to form using conventional casting technologies, thus fabrication of the airfoils using a DMLM process or an electron-beam melting process has been proposed. With the layers built upon one another and joined to one another cross-section by cross-section, an airfoil or portion thereof, such as for a repair, with the required geometries, may be produced. The airfoil may require post-processing to provide desired structural characteristics.